我将Fortran、C和c++的速度与netlib中的经典Levine-Callahan-Dongarra基准进行了比较。使用OpenMP的多语言版本是 http://sites.google.com/site/tprincesite/levine-callahan-dongarra-vectors C语言更丑陋，因为它一开始是自动翻译，加上某些编译器的限制和pragmas插入。 c++就是在适用的地方使用STL模板的C。在我看来，STL在是否能提高可维护性方面好坏参半。

为了了解自动函数内联在多大程度上改进了优化，只需要进行很少的练习，因为示例基于传统的Fortran实践，其中很少依赖内联。

到目前为止使用最广泛的C/ c++编译器缺乏自动向量化，而这些基准测试严重依赖于此。

关于这之前的帖子:在Fortran中使用括号来指示更快或更准确的求值顺序的例子有两个。已知的C编译器没有在不禁用更重要的优化的情况下观察括号的选项。

There is another item where Fortran is different than C - and potentially faster. Fortran has better optimization rules than C. In Fortran, the evaluation order of an expressions is not defined, which allows the compiler to optimize it - if one wants to force a certain order, one has to use parentheses. In C the order is much stricter, but with "-fast" options, they are more relaxed and "(...)" are also ignored. I think Fortran has a way which lies nicely in the middle. (Well, IEEE makes the live more difficult as certain evaluation-order changes require that no overflows occur, which either has to be ignored or hampers the evaluation).

另一个更聪明的规则领域是复数。这不仅是因为直到c99才有了它们，而且Fortran中管理它们的规则更好;由于gfortran的Fortran库部分是用C编写的，但实现了Fortran语义，GCC获得了这个选项(也可以用于“普通”C程序):

-fcx-fortran-rules 复杂的乘法和除法遵循Fortran规则。范围缩减是作为复杂除法的一部分进行的，但是没有检查复杂乘法或除法的结果是否是“NaN + I*NaN”，试图在这种情况下挽救这种情况。

The alias rules mentioned above is another bonus and also - at least in principle - the whole-array operations, which if taken properly into account by the optimizer of the compiler, can lead faster code. On the contra side are that certain operation take more time, e.g. if one does an assignment to an allocatable array, there are lots of checks necessary (reallocate? [Fortran 2003 feature], has the array strides, etc.), which make the simple operation more complex behind the scenes - and thus slower, but makes the language more powerful. On the other hand, the array operations with flexible bounds and strides makes it easier to write code - and the compiler is usually better optimizing code than a user.

总的来说，我认为C和Fortran的速度差不多;选择应该更多的是你更喜欢哪种语言，或者是使用Fortran的全数组操作及其更好的可移植性更有用，还是使用C中更好的系统接口和图形用户界面库。

这两种语言具有相似的特性集。性能上的差异来自Fortran不允许混淆的事实，除非使用了EQUIVALENCE语句。任何有别名的代码都不是有效的Fortran，但是它是由程序员而不是编译器来检测这些错误的。因此，Fortran编译器忽略了可能的内存指针别名，并允许它们生成更有效的代码。看一下C语言中的这个小例子:

void transform (float *output, float const * input, float const * matrix, int *n)
{
    int i;
    for (i=0; i<*n; i++)
    {
        float x = input[i*2+0];
        float y = input[i*2+1];
        output[i*2+0] = matrix[0] * x + matrix[1] * y;
        output[i*2+1] = matrix[2] * x + matrix[3] * y;
    }
}

这个函数在优化后会比Fortran函数运行得慢。为什么如此?如果你在输出数组中写入值，你可能会改变矩阵的值。毕竟，指针可以重叠并指向相同的内存块(包括int指针!)C编译器被迫从内存中重新加载所有计算的四个矩阵值。

在Fortran中，编译器只加载一次矩阵值，并将它们存储在寄存器中。它可以这样做是因为Fortran编译器假定指针/数组在内存中不重叠。

Fortunately, the restrict keyword and strict-aliasing have been introduced to the C99 standard to address this problem. It's well supported in most C++ compilers these days as well. The keyword allows you to give the compiler a hint that the programmer promises that a pointer does not alias with any other pointer. The strict-aliasing means that the programmer promises that pointers of different type will never overlap, for example a double* will not overlap with an int* (with the specific exception that char* and void* can overlap with anything).

If you use them you will get the same speed from C and Fortran. However, the ability to use the restrict keyword only with performance critical functions means that C (and C++) programs are much safer and easier to write. For example, consider the invalid Fortran code: CALL TRANSFORM(A(1, 30), A(2, 31), A(3, 32), 30), which most Fortran compilers will happily compile without any warning but introduces a bug that only shows up on some compilers, on some hardware and with some optimization options.

Fortran可以非常方便地处理数组，特别是多维数组。在Fortran中对多维数组元素进行切片比在C/ c++中容易得多。c++现在有库可以做这项工作，比如Boost或Eigen，但它们毕竟是外部库。在Fortran中，这些函数是固有的。

对于开发来说，Fortran是更快还是更方便主要取决于您需要完成的工作。作为地球物理的科学计算人员，我用Fortran(我指的是现代Fortran， >=F90)进行了大部分计算。

使用现代标准和编译器，不!

Some of the folks here have suggested that FORTRAN is faster because the compiler doesn't need to worry about aliasing (and hence can make more assumptions during optimisation). However, this has been dealt with in C since the C99 (I think) standard with the inclusion of the restrict keyword. Which basically tells the compiler, that within a give scope, the pointer is not aliased. Furthermore C enables proper pointer arithmetic, where things like aliasing can be very useful in terms of performance and resource allocation. Although I think more recent version of FORTRAN enable the use of "proper" pointers.

对于现代实现，C通用优于FORTRAN(尽管它也非常快)。

http://benchmarksgame.alioth.debian.org/u64q/fortran.html

编辑:

一个公平的批评似乎是，基准测试可能是有偏见的。这里是另一个来源(相对于C)，将结果放在更多的上下文中:

http://julialang.org/benchmarks/

你可以看到C在大多数情况下优于Fortran(再次看到下面的批评也适用于这里);正如其他人所指出的，基准测试是一门不精确的科学，很容易偏袒一种语言而不是其他语言。但它确实说明了Fortran和C语言有相似的性能。

一般来说，FORTRAN比C慢。C可以使用硬件级指针，允许程序员手动优化。FORTRAN(在大多数情况下)不能访问硬件内存寻址黑客。(VAX FORTRAN是另一回事。)我从70年代开始断断续续地使用FORTRAN。(真的)。

然而，从90年代开始，FORTRAN已经发展到包括特定的语言结构，可以优化成内在的并行算法，真正可以在多核处理器上运行。例如，自动矢量化允许多个处理器同时处理数据向量中的每个元素。16个处理器——16个元素向量——处理需要1/16的时间。

在C语言中，您必须管理自己的线程并为多处理仔细设计算法，然后使用一堆API调用来确保并行性正确发生。

在FORTRAN中，您只需要为多处理仔细设计算法。编译器和运行时可以为您处理其余的工作。

您可以阅读一些关于高性能Fortran的内容，但是您会发现许多死链接。你最好阅读并行编程(比如OpenMP.org)以及FORTRAN如何支持并行编程。